The latest multi-million political donor is businessman Stuart Wheeler.

A married father of three daughters, 65-year-old Mr Wheeler worked as a barrister before setting up IG Index in 1974.

The company allowed UK residents to speculate on the price of gold at a time when exchange controls prevented them from buying it, except at a premium.

A keen gambler, he could also boast having played bridge with Lord Lucan just before the peer vanished, and with Omar Sharif.

He also realised a dream by taking part in the World Poker Championships in Las Vegas.

Eton educated

Educated at Eton, he went on to do his national service in the Welsh Guards before graduating from Oxford with a second class honours degree in law.

He practised as a barrister briefly before working as a merchant banker.

The entrepreneur is married to Tessa Codrington, a society photographer, and they have three daughters.

Sarah, 20, is a student, while Jacquetta, 18, is a Paris catwalk model. The couple's third daughter, Charlotte, 15, is a pupil at King's School, Canterbury.

Over the years, IG's betting business was expanded to include all commodities in the London market, then the US markets, FTSE and Dow Jones indices and other financial figures, such as stock index futures.

Sports betting

In 1993, the company set up a department to take spread bets on sporting events, then a new sector which sky-rocketed during the 1990s to become a highly profitable part of the betting industry.

IG's first non-betting activity began in 1996, when the company started dealing in foreign exchange.

And last year, the company was floated on the London Stock Exchange as IG Group. Its value currently stands at £253m.

Mr Wheeler told the Financial Times in December: "I'm not a compulsive gambler. I'd never buy a lottery ticket or play a fruit machine - the odds are ridiculous - but I've always liked betting on horses and cards, particularly blackjack, because I'm interested in probabilities".

He added: "There's something true about the way people bet: in the 1992 election, the polls were saying Labour, but the betting was for Major. Voters may tell a pollster one thing, but they put their money where they mean it."

On the Tories chances at the next election he is upbeat saying that the odds on a Labour victory are 8/1 and the odds against the Conservatives winning are 9/2.

Mr Wheeler insists those are "precisely the odds" when former Tory leader Sir Edward Heath won his election in 1970.

I want nothing - Wheeler

And he is dismissive that he should be out to gain something for himself through his donation saying: "I don't want anything from them at all."

But it is the incredible size of the donation that has struck most commentators, but as Mr Wheeler suggests, size is a very subjective thing.

"There have been times in my life when £100 has been critical for me but my shares are now worth between £85 and £90m and no family needs anything like that.

"It makes no difference, to be honest, whether we've got £90m or £85m whereas the £5m difference may make a lot to the Tories."